Apple Music Plans

As said, music will only play on one device ( out of any that are using a specific apple ID) at a time

An Individual Apple Music plan cannot be shared across different Apple IDs.

i.e The Individual Music Plan will only be available to the Apple ID that subscribes to it on devices signed in to that Apple ID.

So if your husband's Apple ID is used to subscribe to it, only devices using his Apple ID for iTunes, App Stores and iCloud will have access to it and play music from it. Each device using that Apple ID can play any music they want at any time, but not at the same time. If one device starts playing music while another one is currently playing music, the one that is playing music will stop playing, and the other one will start.

Devices using a different Apple ID will not have any access to that Individual Apple Music subscription.

If you want devices using a different Apple ID to have access to the subscription it needs to be a Family Plan.

With a Family Plan, you play music on up to 6 devices(with 6 different Apple IDs) simultaneously, and it can be any music you want, and does not have to be the same music on all or any of the devices. i.e each device can choose what it wants to play.

Only if you don't plan on listening to music on more than one device at a time. Apple Music will only ever play on one device at a time per Apple ID.

If you use Family Sharing and a Family Apple Music Plan, you still need separate Apple IDs to be able to play Apple Music on 2 or more devices at a time.

Also its a really really bad idea to share Apple IDs. An Apple ID is meant to be used by a single person.

No, Apple Music only allows you to listen on one device at a time if on the same Apple ID.

You will need to have separate Apple ID's also if you do the Family Sharing option.

You're welcome.